Microneedle technology provides a useful minimally-invasive method to sample blood. Due to their small size, microneedles can pierce skin and take minute quantities of blood with minimal impact and or pain to the subject. In spite of their advantages, microneedle systems are still somewhat invasive since they involve the extraction of blood from the patient.
Implanted in vivo sensors provide another means to sample blood chemistry that does not require blood extraction. Unfortunately, in vivo sensors interact with the physiology and are susceptible to degradation during use. It would be desirable to achieve a less invasive approach that would not extract blood from the patient and provide longer measurement times than in prior art in vivo devices.